It is sometimes desirable to insert a medical device (e.g., a catheter, needle, cannula or other delivery device) into a particular target area (e.g., within a certain type of tissue, a lesion, tumor, necrotic or infracted area, etc.) within the body of a human or animal subject. For example, when it is desired to deliver a diagnostic or therapeutic modality or substance (e.g., dye, a drug, a biologic, cells, a gene therapy preparation, nutrients, radiation, heat, etc.) or a device (e.g., an electrode, sensor, substance delivery device, etc.) to a particular target location within a subject's body, a catheter, needle, cannula or other delivery apparatus may be inserted and advanced through the body until it is positioned within the target area. Thereafter, the diagnostic or therapeutic modality, substance or device is delivered into the target area via that catheter, needle, cannula or other delivery apparatus. In some cases, the medical device (e.g., a catheter, needle, cannula or other delivery device) is inserted directly from a location outside the subject's body and into the target area. In other cases, an intervening device may be used to facilitate such placement of the medical device. For example, in some procedures, a penetration catheter is initially inserted into the subject's vasculature and advanced into a blood vessel near the target area. A penetrator (e.g., a hollow needle) is then advanced from the penetration catheter into tissue adjacent to the blood vessel lumen in the general direction of the target area and the catheter, needle, cannula or other delivery apparatus is then advanced through the penetrator, through intervening tissue and into the target area. Examples of such procedures include those described in U.S. Pat. Nos. 5,830,222 (Makower), 6,068,638 (Makower), 6,159,225 (Makower), 6,190,353 (Makower, et al.), 6,283,951 (Flaherty, et al.), 6,375,615 (Flaherty, et al.), 6,508,824 (Flaherty, et al.), 6,544,230 (Flaherty, et al.), 6,579,311 (Makower), 6,602,241 (Makower, et al.), 6,655,386 (Makower, et al.), 6,660,024 (Flaherty, et al.), 6,685,648 (Flaherty, et al.), 6,709,444 (Makower), 6,726,677 (Flaherty, et al.) and 6,746,464 (Makower), the entire disclosure of each such United States patent being expressly incorporated herein by reference.
Determining when the catheter, needle, cannula or other delivery apparatus has entered the intended target area can present a challenge. In some instances, radiographic imaging can be used to determine when the target area has been entered. However, this approach requires that the target area be radiographically distinguishable from surrounding tissue. The use of radiographic guidance can also require extended fluoroscopy or multiple x-rays with the resultant expense and radiation exposure to the subject and medical personnel performing the procedure.
An optical system that is convenient and useable to guide the positioning of a catheter, cannula, needle or other medical device within a particular target area, without the use of radiation, is desirable. Preferably, such an optical system would not only sense when the catheter, cannula, needle or other medical device has entered the target area but may also be used to track the device during insertion and removal.
The prior art has included a number of optical devices which purportedly may sense the location of a catheter or device within a body. For example, U.S. Pat. No. 5,423,321 (Fontenot) describes a catheter that has multiple light guiding fibers of different lengths. The catheter is inserted into an organ or vessel and visible or near infrared light is delivered through the light guiding fibers. The light emitted from the catheter is then observed through the wall of the organ or vessel, thereby indicating the position of the catheter. A detection system is also described for determining when a surgical cutting tool approaches the vessel.
U.S. Pat. No. 7,273,056 (Wilson et al.) describes an optically guided catheter wherein a small laser diode is inserted in a distal end of the catheter and light from the laser diode is passed through an optical fiber that extends through the catheter. The light is selected to be of a wavelength that is minimally absorbed by tissue, preferably in the range from about 620 nm to 1100 nm. 780 nm is preferably used as this is where the tissue absorption is near a minimum. The light passes out the end of the fiber (at the proximal end of the catheter) and through the tissue to the outside of the patient's skin where it is measured. The light pattern is observed by night vision goggles that filter out other frequencies of light. The detected light permits location of the end of the fiber, the positional accuracy depending on the thickness of tissue between the fiber tip and the exterior of the body. The method is highly accurate for small children and for catheters within a few centimeters of the skin surface of adults.
Thus, there remains a need in the art for the development of new devices and methods for optically guided positioning of catheters, cannulae, needles and other devices within specific intracorporeal target areas.